Tube-shell heat exchanger



1967 w. H. POORE.

TUBE-SHELL HEAT EXCHANGER Filed June 21, 1965 /VlV////////////////INVENTOR. WILLIAM H Poo/a5 0 4 w n E .1 MM m/% A TTOR/VEVS United StatesPatent 3,301,321 TUBE-SHELL HEAT EXCHANGER William H. Poore, Livonia,Mich, assignor to American Radiator & Standard Sanitary Corporation, NewYork, N.Y., a corporation of Delaware Filed June 21, 1965, Ser. No.465,374 9 Claims. (Cl. 165-178) This invention relates to tube-shellheat exchangers, and particularly heat exchangers employing flexibletubes within the shell.

Recently heat exchangers employing flexible tubes of plastic materialhave been proposed for the cooling or heating of fluids which wouldcorrode copper or other metal heat exchange tubes. The plastic tubes areflexible and limp like spaghetti. Hence there is a problem in installingthe tubes in the shell, and supporting them after installation.

A primary object of the present invention is to provide a tubeshell heatexchanger wherein flexible tubes can be readily installed in the shelland supported adequately after their installation.

Another object is to provide a tube-shell heat exchanger wherein themechanism for supporting the flexible tubes is comprised of a relativelysmall number of parts.

Other objects of this invention will appear from the followingdescription, accompanying drawing, and appended claims.

In the drawing:

The single figure is a longitudinal sectional view taken through atube-shell heat exchanger constructed according to the invention.

Before explaining the present invention in detail, it is to beunderstood that the invention is not limited in its application to thedetails of construction and arrangement of parts illustrated in theaccompanying drawing, since the invention is capable of otherembodiments and of being practiced or carried out in various ways. Also,it is to be understood that the phraseology or terminology employedherein is for the purpose of description and not of limitation.

In the drawing there is shown a tube-shell heat exchanger comprising arigid cylindrical metal shell 10 having a fluid inlet 12 and fluidoutlet 13. The upper end of the shell is flanged at 15 to receive theplastic tube sheet 16 which supports and has mounted therein a largenumber of flexible plastic tubes 18. Positioned against the upper endface of tube sheet 16 is the flange 19 of a bonnet or header which isequipped with an inlet 22 for directing fluid into the tubes 18.

The lower ends of tubes 18 extend through and are anchored in a floatingplastic tube sheet 23 which includes a relatively large diametercylindrical section 25, a slightly smaller diameter cylindrical section26 and an intermediate reduced-diameter section which forms a groove 28.In the assembled condition of the heat exchanger, section 25 of thelower tube sheet has its periphery sealingly engaged with a compressedO-ring seal 30 which is positioned in a groove in the flange 32 of shell10. The periphery of section 26 sealingly engages a compressed O-ringseal 33 which is positioned in a groove in a flange 35 of a bonnet orheader 36. Interposed between flanges 32 and 35 is a split ring 38comprised of two semi-annular ring shaped discs, suitable bolts 50 beingtrained through openings in the flanges and interposed discs 38 tosecure the components in their illustrated positions. It will be seenthat fluid introduced into inlet 22 flows through the tubes 18 into theheader 36 and out through outlet 52. The shell fluid introduced throughinlet 12 flows around the outer surfaces of tubes 18 and out throughoutlet 13. Split ring 38 constitutes a detent means to retain tube sheet23 in its shown position.

on the order of two to twelve inches.

3,3l,32l Patented Jan. 31, 1967 In the illustrated heat exchanger, tubes18 and tube sheets 16 and 23 are formed of plastic material, the ends ofthe tubes being bunched together and inserted into a central opening ineach tube sheet for securement therein by a process not part of thepresent invention. For purposes of this invention the tubes could beformed of various flexible materials such as elastomers, fabric, helicalmetal coils, or various diflerent plastics. Whatever the tube materialand method of securing the tubes to the tube sheets, the tubes are veryflexible and limp and ofier no support, especially in an axialdirection, unless adequately supported in the shell. For manufacturingreasons the tubes are preferably permanently secured to the tube sheetsbefore insertion of the tube-tube sheet assembly into the shell.

The construction of the tubes and tube sheets makes it diflicult toinstall and adequately support the tube-tube sheet assembly in the heatexchanger shell. However, by grooving and dimensioning the lower tubesheet 23 as shown in the drawing, it is possible to readily install thetube-tube sheet assembly into the shell in a single operation.

Thus, with bonnets 28 and 36 dissociated from shell 10 and the shell inan upright position, the tube-tube sheet assembly can be lowered ordropped into the shell and the peripheral surface of tube sheet 23allowed to slide downwardly along the inner surface 55 of cylindricalshell 10.

It will be noted that section 26 of the tube sheet has a smallerdiameter than section 25; this allows section 26 to pass freely throughpre-placed O-ring 30 without being restrained. Section 26 can thus takea position slightly below the lower edge of shell 10, after which thetube sheet can be manually pulled down to cause section 25 to be grippedby O-ring 30 with sufficient friction to form the desired seal. Whentube sheet 23 is in its illustrated position the two separated parts ofsplit ring 38 can be installed on the lower face of flange 32 and movedradially inwardly into groove 28. Then bonnet 36 can be installed, andbolts 58 utilized to secure the parts in their illustrated positions.Suitable bolts 56 can be utilized to secure bonnet 26 against the upperface of tube sheet 16. During installation of bonnet 36 (withpre-positioned O- ring 33 therein) split ring 38 may act as an abutmentto prevent excessive upward displacement of the tube sheet. Tube sheetsection 26 has a diameter which is sufliciently less than theuncompressed inner diameter of O-ring 30 as will enable the tube sheetto fall to its illustrated position during installation of the tubebundle. O-ring 33 is however made with an inner diameter of sufficientlysmall dimension as to provide an interference fit with the surface oftube sheet section 26 when header 36 is pushed upwardly against splitring 38. Within the broader aspects of the invention the groove 29 andring 38 relationship could be replaced with differently configuredstructures, as for example radial holes in the intermediate peripheralsurface of sheet 23 and cooperating set screws or pins carried by shell10.

The heat exchanger can be formed to different sizes, but as an examplethe shell can be on the order of one to ten feet in length and the tubebundle can have a diameter These dimensions would make installation ofthe tube-tube sheet assembly quite difficult except for the specialconstruction of the lower tube sheet.

Groove 28 is preferably made slightly wider than the axial thickness ofsplit ring 38 to compensate for manufacturing variations in partsdimensions, as for example the length of shell 10. If the heat exchangeris used in a horizontal prone position, the weight of spaghetti-liketubes 18 will tend to draw tube sheeet 23 toward tube sheet 16. Howevershoulder 29 formed by groove 28 will hold the tube sheet 23 in astationary position. In service seal 30 seals shell space 57 from theambient, and seal 33 seals space 59 from the ambient; the two sealscollectively seal spaces 57 and 59 from one another.

It will be understood that the drawing and description are merelyillustrative of the principles of the invention, and that variations instructure and dimension may be resorted to without departing from thespirit .of the invention as set forth in the appended claims.

What is claimed is:

1. A heat exchanger comprising a shell; flexible fluid tubes extendingwithin the shell; means floatably supporting the tubes adjacent one endof the shell; a header lo cated at said one end of the shell andoperable to admit fluid to or withdraw fluid from the tubes; detentmeans rigid with the header and shell for limiting axial movement of thefloating tube support means; first seal means located between the shelland tube support means for sealing the shell space from atmosphere; andsecond seal means located between the header and tube support means forsealing the header space from atmosphere.

2. The heat exchanger of claim 1 wherein the tube support meanscomprises an axially thickened tube sheet having a groove in itsperipheral surface, and said limiting means comprises detent mechanismprojecting into the groove; the groove having a greater axial dimensionthan the detent mechanism, whereby the tube sheet is free for limitedaxial movement in either direction.

3. A heat exchanger comprising a shell; flexible fluid tubes extendingwithin the shell; a tube sheet floatably positioned within one end ofthe shell and having the tubes secured thereto; said tube sheet having agroove in its outer periphery; a header located at said .one end of theshell and operable to admit fluid to or withdraw fluid from the tube;tube sheet retainer means clamped between the shell and header, andprojecting into the aforementioned groove to limit axial movement of thetube sheet; first seal means mounted in the shell and engaging theperipheral surface of the tube sheet to seal the shell space fromatmosphere; and second seal means mounted in the header and engaging theperipheral surface of the tube sheet to seal the header spacefrom.atmosphere.

4. A heat exchanger comprising a shell; flexible fluid tubes extendingwithin the shell; an axially elongated tube sheet floatably positionedwithin one end of the shell and having the tubes secured thereto; saidtube sheet having a first groove in its outer periphery; a headerlocated at said one end of the shell and operable to admit fluid to orwithdraw fluid from the tubes; apertured flanges formed on the shell andheader; apertured sheet retainer means sandwiched between the shellflange and header flange, and projecting into the aforementioned grooveto limit axial movement of the tube sheet; connectors extending throughthe apertures to secure the retainer means, shell and header together; asecond groove in a surface of the shell facing the periphery of the tubesheet; an O-ring positioned in said second groove to seal the shellspace from the atmosphere; a third groove in a surface of the headerfacing the periphery of the tube sheet; and a second O-ring positionedin the third groove to seal the header space from the atmosphere.

5. A heat exchanger comprising an elongated shell; a first tube sheetengaging an end surface of the shell; flexible fluid tubes permanentlyanchored to said tube sheet and extending within the shell; a secondtube sheet permanently anchored to the tubes and engaging an innersurface of the shell; said second tube sheet having a groove in itsperiphery; retainer means abutting the other end surface of the shelland extending into the groove; a fluid header means abutting theretainer means and having an inner surface thereof engaging theperiphery of the second tube sheet; the peripheral outline of the secondtube sheet being no larger than the inner cross sectional dimension ofthe shell whereby the tube-tube sheet assembly is installable in andremovable from the shell by movement through the portion of the shellwhich defines the first mentioned end surface; first seal meansinterposed between the second tube sheet and shell, and second sealmeans interposed between the fluid header means and second tube sheet.

6. A heat exchanger comprising an elongated shell; =a first tube sheetsecured to one end of the shell; flexible fluid tubes extending fromsaid tube sheet within the shell; a second tube sheet carried by theends of the tubes remote from the first tube sheet; said second tubesheet comprising a first relatively large diameter section conforming tothe internal diameter of the shell, and a second section of smallerdiameter than the first section; said second tube sheet being positionedwith its first section disposed Within the shell and its second sectionbeyond the shell; a first seal carried by the shell and having aninterference fit with the first section of the second tube sheet toprevent fluid flow therepast; header means located beyond an end of theshell and having an internal surface surrounding the periphery of thesecond section of the second tube sheet; and a second seal carried bythe header means and having an interference fit with the second sectionof the second tube sheet to prevent fluid flow therepast.

7. The heat exchanger of claim 6 and further comprising detent meansoperable to prevent axial movement of the second tube sheet.

8. A heat exchanger comprising an elongated shell; a first tube sheetsecured to one end of the shell; flexible fluid tubes extending fromsaid tube sheet within the shell; a second tube sheet carried by theends of the tubes remote from the first tube sheet; said second tubesheet comprising a first relatively large diameter section conforming tothe internal diameter of the shell, and a second section of smallerdiameter than the first section; said second tube sheet being positionedwith its first section disposed within the shell and its second sect-ionbeyond the shell; a first seal carried by the shell and having aninterference fit with the first section of the second tube sheet toprevent fluid flow therepast; header means located beyond an end of theshell and having an internal surface surrounding the periphery of thesecond section of the second tube sheet; and a second seal carried bythe header means and having an interference fit with the second sectionof the second tube sheet to prevent fluid flow therepast; the outerdiameter of the second section of the second tube sheet beingsufliciently less than the inner diameter of the first seal as to permitsaid second section to pass through the first seal without frictionalinterference between the seal and second section.

9. The heat exchanger of claim 8 wherein the second tube sheet is formedwith a peripheral groove between its first and second sections; the heatexchanger further comprising detent means rigid with the shell andprojecting into the groove to prevent substantial axial movement of thesecond tube sheet.

References Cited by the Examiner UNITED STATES PATENTS 1,779,890 10/1930Rathbun 82 FOREIGN PATENTS 4/ 1909 Germany. 4/1957 Germany.

1. A HEAT EXCHANGER COMPRISING A SHELL; FLEXIBLE FLUID TUBES EXTENDINGWITHIN THE SHELL; MEANS FLOATABLY SUPPORTING THE TUBES ADJACENT ONE ENDOF THE SHELL; A HEADER LOCATED AT SAID ONE END OF THE SHELL AND OPERABLETO ADMIT FLUID TO OR WITHDRAW FLUID FROM THE TUBES; DETENT MEANS RIGIDWITH THE HEADER AND SHELL FOR LIMITING AXIAL MOVEMENT OF THE FLOATINGTUBE SUPPORT MEANS; FIRST SEAL MEANS LOCATED BETWEEN THE SHELL AND TUBESUPPORT MEANS FOR SEALING THE SHELL SPACE FROM ATMOSPHERE; AND SECONDSEAL MEANS LOCATED BETWEEN THE HEADER AND TUBE SUPPORT MEANS FOR SEALINGTHE HEADER SPACE FROM ATMOSPHERE.